From #farm to #fork: identical #clones and Tn6674-like elements in #linezolid-resistant #Enterococcus faecalis from #food-producing #animals and #retail meat (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

From farm to fork: identical clones and Tn6674-like elements in linezolid-resistant Enterococcus faecalis from food-producing animals and retail meat

Houyem Elghaieb, Ana P Tedim, Mohamed S Abbassi, Carla Novais, Bárbara Duarte, Abdennaceur Hassen, Luísa Peixe, Ana R Freitas

Journal of Antimicrobial Chemotherapy, dkz419,

Published: 11 October 2019




Increasing numbers of linezolid-resistant Enterococcus carrying optrA are being reported across different niches worldwide. We aimed to characterize the first optrA-carrying Enterococcus faecalis obtained from food-producing animals and retail meat samples in Tunisia.


Seven optrA-carrying E. faecalis obtained from chicken faeces (n = 3, August 2017) and retail chicken meat (n = 4, August 2017) in Tunisia were analysed. Antimicrobial susceptibility was determined by disc diffusion, broth microdilution and Etest against 13 antibiotics, linezolid and tedizolid, respectively (EUCAST/CLSI). optrA stability (∼600 bacterial generations), transfer (filter mating) and location (S1-PFGE/hybridization) were characterized. WGS (Illumina-HiSeq) was done for four representatives that were analysed through in silico and genomic mapping tools.


Four MDR clones carrying different virulence genes were identified in chicken faeces (ST476) and retail meat (the same ST476 clone plus ST21 and ST859) samples. MICs of linezolid and tedizolid were stably maintained at 8 and 1–2 mg/L, respectively. optrA was located in the same transferable chromosomal Tn6674-like element in ST476 and ST21 clones, similar to isolates from pigs in Malaysia and humans in China. ST859 carried a non-conjugative plasmid of ∼40 kb with an impB-fexA-optrA segment, similar to plasmids from pigs and humans in China.


The same chromosomal and transferable Tn6674-like element was identified in different E. faecalis clones from humans and animals. The finding of retail meat contaminated with the same linezolid-resistant E. faecalis strain obtained from a food-producing animal highlights the potential role of the food chain in the worrisome dissemination of optrA that can be stably maintained without selective pressure over generations.

Topic: antibiotics – enterococcus – plasmids – diffusion – chickens – china – chromosomes – clone cells – electrophoresis, gel, pulsed-field – enterococcus faecalis – feces – food – food chain – genes – genome – malaysia – meat – suidae – tunisia – virulence – linezolid – antimicrobial susceptibility – transfer technique – filters – mating – tedizolid – malnutrition-inflammation-cachexia syndrome – whole genome sequencing


© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email:

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Keywords: Antibiotics; Drugs Resistance; Linezolid; Enterococci; Pigs; Poultry; Food Safety; Plasmids.


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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum ( in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.